The background description provided herein is for the purpose of generally presenting the context of the present invention. The subject matter discussed in the background of the invention section should not be assumed to be prior art merely as a result of its mention in the background of the invention section. Similarly, a problem mentioned in the background of the invention section or associated with the subject matter of the background of the invention section should not be assumed to have been previously recognized in the prior art. The subject matter in the background of the invention section merely represents different approaches, which in and of themselves may also be inventions. Work of the presently named inventors, to the extent it is described in the background of the invention section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present invention.
As shown in FIG. 1, a linear compressor has a casing 1. An air inlet 1a for a refrigerant to enter and a vent 1b for discharging the refrigerant are opened on the casing 1. A motor 2 and an oil supply pipe 3 for conveying a lubricant 6 to the motor 2 are installed inside the casing 1. The motor 2 has a shell 21. The shell 21 is supported on an inner wall surface of the casing 1 by using multiple springs. Parts such as a cylinder 11, a piston 12, a compression cavity 18, a discharging cavity 19 connected to the vent 1b, an inner stator 14, a coil 17 placed inside the inner stator 14, an outer stator 15, a rotor 16, and a rotor frame 22 are installed inside the shell 21. Of them, the cylinder 11, the inner stator 14, the outer stator 15 and the rotor 16 are cylindrical. The outer stator 15 is fixed on an inner wall surface of the shell 21.
A front flange 13 that provides a fixing effect is disposed at the right end (corresponding to the right side of FIG. 1) of the shell 21. The front flange 13, the cylinder 11, the compression cavity 18, the discharge cavity 19, the inner stator 14, and the coil 17 are connected together to the outer stator 15 and the shell 21. During the movement of the piston 12, the movements of these members are synchronized. The rotor 16 is fixed on the rotor frame 22, which are both supported between the inner stator 14 and the inner wall surface of the shell 21 through a spring 5. When the coil 17 is electrified, the magnetic field intensity of the magnetic field formed by the inner stator 14 and the outer stator 15 is changed. Under the magnetic field force, the rotor 16 moves back and forth (in a left-right direction in FIG. 1) along an axis thereof. The rotor 16 actuates, through the rotor frame 22, the piston 12 to move back and forth along the axis of the cylinder 11, so as to compress the refrigerant gas inside the compression cavity 18 to achieve refrigeration.
As shown in FIG. 2 and FIG. 3, the stator of the motor of the linear compressor generally comprises several stator pieces 7 that are circumferentially and sequentially arranged about an axial direction and are radially disposed. Each stator piece 7 may be formed by stacking the same stator laminations, that is, by forming a stator lamination group. Because each stator lamination group is arranged and disposed sequentially along the circumferential direction, certain angles are defined between adjacent stator lamination groups. A gap 8 is defined between the angle and an outer circumference of the inner stator. The greater the radial length of the stator lamination group, the greater the spacing between the adjacent stator lamination groups and the outer circumference of the inner stator is, and the greater the gap 8 is. Especially, a stator with a coil inside usually has a relatively large volume, and thus cannot be fixed as tight as a stator without a coil.
Because of the gap 8, a small quantity of silicon steel sheets is actually used, and magnetic saturation occurs easily. When magnetic saturation is reached, if a current is further increased, the magnetic field intensity no longer increases. Magnetic saturation occurring to stacked silicon steel sheets, it becomes difficult to increase the capacity of a motor. A potential problem for the linear compressor may be that an electromagnetic force fails to drive a piston to the top dead center, therefore the compression efficiency is lowered and the efficiency of the motor is lowered.
In addition, when the motor is electrified and working, after an alternating current flows through the excitation coil on the inner stator, an induced magnetic field is produced between the inner stator and the outer stator, the interval defined between the combination forms a magnetically conductive resistance to cause a magnetic loss, therefore lower the efficiency of the motor of the compressor.
Further, because there are a number of gaps within the stators, a fringe effect exists in the magnetic field around the gap, which causes the coil of the additional loss and a relatively high temperature rise, and in severe cases, the safety and service life of the motor are affected. To avoid the occurrence of magnetic saturation, the volume of a stator in which a coil is placed may be increased to lower the magnetic flux density; however, this causes an increased volume of the motor of the linear compressor, and further causes an increased volume of the compressor.
Moreover, in the process of manufacturing the linear compressor, these stator laminations need to be fixed to form into a cylindrical part. For the existing linear compressors, stator laminations are mainly fixed by two methods, specifically:
1) A corresponding protrusion or groove is stamped on the stator laminations, and adjacent stator laminations fit each other by using these protrusions and grooves. By using this method, stator laminations are not securely fixed, and become loose easily when a motor vibrates during working.
2) As shown in FIG. 4 and FIG. 5, grooves are defined at the side end of each stator lamination. When these stator laminations are formed into a cylindrical part, an annular fixing component 4 is configured in interference fit manner inside an annular space define within a groove. Because interference fit is needed in this method, during assembly, because of the effect of pressure, deformation can easily occur to a stator lamination, so that the overall size assembly precision of a linear compressor of a motor is affected.
Therefore, a heretofore unaddressed need exists in the art to address the aforementioned deficiencies and inadequacies.